According to conventional practice, joints in lead anodes used in the mining industry are formed using traditional lead burning procedures (e.g., torch welding) in which lead is melted by hand to form the welds or joints. There are, however, a number of disadvantages associated with conventional lead burning procedures as will be discussed below.
Conventional lead burning procedures involve a high degree of risk to the worker. First, the heat generated during creation of the weld can result in worker injury. Second, during melting of the lead, the ambient levels of lead can rise to toxic levels. If inhaled, it could lead to lead poisoning, one of the oldest forms of occupational hazards. As a result, a variety of bodily processes are affected, as well as the deterioration of numerous organs such as the heart, bones, intestines, kidneys, and reproductive and nervous systems.
Conventional lead burning procedures often produce anodes having defective welds which have repeatedly lead to product failure. By training and using a specially skilled work force, the potential for defective welds can be reduced, but is not eliminated, as incomplete welds can occur despite use of skilled workers. In these incomplete welds, the joint visually appears sound. However, the two melt pools created to form the weld have never merged, thereby greatly reducing the material available in the anode joint for current transport and creep (i.e., deformation) resistance.
Even when an anode having a defect-free joint is created, conventional lead burning procedures create an undesirable heat affected zone in the base metal structure around the region of the anode joint. In this heat affected region, the grain structure of the materials in the anode is altered by the heat used to create the joint. The altered grain structure can be a further source of reduced corrosion resistance and decreased creep resistance.
Moreover, lead and copper (used to create anodes) do not naturally weld together. As such, various techniques, such as soldering, are utilized in conventional lead burning procedures to join the lead and copper, thereby constructing the anode. Therefore, in addition to the foregoing disadvantages, conventional anode manufacturing processes are more costly due to the increased manufacturing time and materials involved in joining the lead and copper.
Accordingly, since conventional lead burning techniques used to produce anodes are rife with problems, companies must devote costly resources to safety, worker training, quality control testing, and manufacturing. To date, conventional lead burning techniques have failed to adequately address these issues in the anode industry.
In view of the foregoing, there is a need in the art for an anode manufacturing technique which greatly reduces or eliminates the disadvantages of the prior art.